Sorry for creating a separate thread, but there are so many threads about this topic already...

I recently upgraded the operating system on my hp tx2500 tablet pc (tx2524ca) from 64bit Vista Home Premium (+ Bloatware) to 64bit Windows 7 Professional. Can't recommend it highly enough.
But... like a lot of people I lost pressure sensitivity in Photoshop (32bit CS5, 64bit CS5, 32bit Elements2, don't laugh) & OpenCanvas4.5ePlus, although not in MS Office 2007 or pen tablet input.
tx2500 series have Wacom TabletPC Digitizer, so that appeared to be the issue.
I tried pretty much everything i could find on the web, nothing worked. until...

as of present, most current driver version is 7.0.1.8 (Date= 02-Nov-2010). name of file is isd701-8_int.exe or ISD_DualTouch_701-8.exe depending on site downloaded from. but wacom continually updates it

Install tabletpc driver. Restart.

But... apparantly "the installer does not install the proper dll's in C:\Windows\SysWOW64, It only installs the 64 bit driver in there."

So, unzip the Driver package. to do this, I copied and pasted the driver download package file, renamed extension from .exe to .zip, then unzipped the driver package

Locate 2 files in ISD_DualTouch_701-8\System32\64\32\

(ISD_Tablet.dll,Wintab32.dll)

copy and paste these 2 files into to C:\Windows\SysWOW64\
(I archived the existing Wintab32.dll, it appeared to be the version of the file located in ISD_DualTouch_701-8\System32\64
-apparently you can't have both versions present???)

-Restart
-Pressure sensitivity restored!!! Happy Photoshopping!!!!

All my pressure sensitivity seems to be restored. Note that I have disabled the touch function on my screen (it interfered with my pen use) so I can't comment if it works or not.